SEED-TESTING.

New Zealand Journal of Agriculture, Volume XVIII, Issue 3, 20 March 1919, Page 129

SEED-TESTING.

THE NEW ZEALAND OFFICIAL SYSTEM.

By

E. BRUCE LEVY,

Biological Laboratory.

seed-testing is by no means an innovation in the OFFICIAL seed-testing is no means an innovation official history of agricultural progress. Over forty years ago official seed-testing stations were in operation on the Continent- of Europe. Ireland has been testing seeds for sixteen years, Scotland for six years, and in 1917 Great Britain, as a war measure, established a station and issued an Order for the compulsory testing of the main agricultural seeds used within its borders.

The seed-testing station of the New Zealand Department of Agriculture has now been established for ten years, but so far no enactment has been passed making seed-testing compulsory in the Dominion. The necessity for compulsory testing has been obviated to a large extent by the seed-merchants themselves recognizing the necessity of knowing the quality of the goods they are offering. In the main it is the high-grade or larger merchant who forwards seeds for test, and it seems feasible to conclude that if these merchants are unable to satisfactorily fix the quality of their seeds the smaller merchant with

his less skilled assistance must needs be trading in an article the value of which he is not able correctly to assess. As indicated, general seed-testing by the Department was inaugurated in 1909. Before that period a great deal of seed-testing work of a more or less experimental nature had been carried out, and many preliminary expedients were adopted before the -Department announced that a seed-testing station had been established. Seeds were tested free, the test including a statement of the average germination capacity and the percentage and kinds of extraneous seeds. In 1916, however, in order to place the system on a businesslike basis, fees were fixed for merchants' samples, the amounts being is. per sample, for germination tests, 2s. for germination and purity, and for seed-mixtures is. for each constituent of the mixture. Testing is still carried out free of charge for farmers. . '

For the eleven months ended February, 1919, 4,417 samples have been tested, thus making an aggregate of 20,315 samples dealt with

since the establishment of the system.

It is gratifying to note that by far the greatest proportion of the samples are sent in by seed-mer-chants, the farmer as a general rule .accepting the statement of his seedsman that the . seed is reliable and of good value. .The farmer, after his crop has failed to establish, sometimes sends in samples for test perhaps with the hope that he may be able to claim compensation from his seedsman if the test proves that the seed was of low vitality. There should be no need, however, for the farmer to have to bother getting his seeds tested. Too long a time must elapse between his procuring the samples and his receipt of the result of the test. If the test is unsatisfactory he must procure fresh samples and again wait for results. Testing

for farmers is practically useless as far as their actual sowings are concerned. What the farmer requires is to have the germination supplied

him by the ■ seller . at the time he makes his purchase. id;The„sonly satisfactory way in which this can be done is by obligating/ ’the' seller to supply this information—and not only to supply -it, 2.but to be directly responsible if his information is misleading.

These notes, however, are not written to discuss possible or prospective legislation, but aim at setting out what has been accomplished already in the direction of seed-testing, and making more fully known the methods adopted by the Department. It may be mentioned that all the photographs here reproduced illustrate the New Zealand system, having been taken by the writer at the Biological Laboratory.

GENERAL METHODS OF SEED-TESTING.

There are two methods of seed-testing —the Continental method and the Irish method. The essential difference between these is that in the Continental method only those seeds and caryopses that are fully - ' matured are tested for germination, the immature ones being

■counted as impurities. ' In the . Irish method., the ,immature seeds are included in the germination tests. "Neither method, is entirely satisfactory. In the Continental method no value can be attached'to ‘ the .germination alone, the real value, Germination X Purity 4- 100, being

the only real guide to the value of the line of seed. In the Irish method, each immature seed incapable of germination lowers the real value by I per cent., whereas it may weigh less than a mature seed; consequently the real value of the line is to a small extent under-

estimated

The method adopted by the Department here, as in Great Britain,, is the Irish method. In some cases, however, this method is departed from, and the case of Waipu brown-top (Agrostis canina) seed may be cited as an example. This seed usually contains a large percentage of empty glumes, &c., and of these samples mature only are germinated. The percentage by weight of kernel and the percentage

by weight of husk and extraneous seeds are given thus — Empty glumes, &c., 45 per cent. ; kernel, 50 per cent. ; extraneous seed, 5 per cent. ; germination, 85 per cent. The Continental method offers advantages over the Irish- method so far as the actual sale of seeds is concerned, while the Irish method provides the farmer a better and more readily understandable conception of the worth of a line. It is much better for the farmer to know that in a certain line 70 per cent, of the apparent seeds will germinate rather-than to know that 30 per cent. - of the seeds are immature. When they have the Continental germination test merchants almost invariably quote this test and let the farmer examine the line. He sees that it is well dressed, and concludes that if the germination is 90 per cent., then ninety seeds out-of every hundred seeds he sees will germinate. . This is not: so, as there may be up to 30 per cent, of the seeds counted as immature and which are not included in the germination

test. Thus our germination tests are often lower than the Continental ones; but the -purity is higher, as we count as impurities only extraneous seeds, making a special, note when husk, dirt, &c., are excessive, , as is the case of Waipu brown-top just cited. What the farmer' really wants to. know as far as purity is concerned is what foreign seeds are contained in the sample, and when immature seeds of the species sold are included as '.impurities., he receives quite a wrong. impression of the line. '

Theoretically the Continental method is the more correct, the only trouble being the laborious and exact method of execution of tests — so much so that for all practical purposes this method defeats its own end.

THE NEW ZEALAND SYSTEM IN DETAIL.

The detailed methods of germination and purity tests adopted in this Laboratory will now be described. In passing, it may be mentioned that in consulting reports, &c., of European and other seedtesting stations practically no information can be gleaned as to the exact method of conducting the tests. This is to be regretted, as an exchange of ideas should lead to a more perfect system and hence greater efficiency.

When received the samples are given a distinguishing laboratory number. The name of the seed, distinguishing-mark, name of sender, &c., are entered on special record-cards. The date on which the sample is placed to germinate is entered, also the various days on which counts are to be made. The card is then placed in an index of days of the month, so that all cards of a certain date are together, which constitutes the day’s counting. The card system of recording is advantageous not only in ensuring uniformity in periods of counting, but also as forming a permanent record of results.

Process of Germination.

The germinating medium is provided by coarse felt —the underfelt —which is placed on asbestos trays, each tray holding twelve

samples. The felt is well sterilized by boiling before being used, and is surmounted by two plies of blotting-paper. The sample is' well mixed and poured out on a sheet of plain paper, which is laid , on a counting - board. From a portion of the sample a hundred seeds are counted (as they come) and spread out on the germinating-tray alongside .the corresponding sample number. From a further portion of the sample a similar hundred seeds are counted and placed beside a corresponding duplicate number on a separate tray. Each sample is covered by a 3 in. watch-glass, , which is raised on one side by a strip of cork to admit of free ventilation. The trays are then placed in the germinator. . It will . be . noted that each test is conducted in duplicate, the duplicate being taken from a different portion of the sample, placed on a separate tray, and each tray placed in a separate germinator.

Germination of all seeds, with the exception of paspalum, cereals, arid prairie-grass, are conducted at a temperature alternating- from 85° F.-to 65° F.: 85° for eight hours and then let fall to 65° for the remaining period of sixteen hours. Paspalum is germinated ■ in a special oven between temperatures .-alternating from 75 0 ; to 95 0 . Cereals and prairie-grass are germinated at ordinary room temperatures. Peas, tares, &c., are soaked in water for sixteen hours before being placed on felts to germinate. ' '

It will be noted that the essentials of germination tests are (i) an alternating temperature, (2) free ventilation, and (3) a moist atmosphere surrounding seed on all sides.

Purity Analysis.

For purity analysis the percentage by weight is the most important, and only under special conditions is the purity by numbers given. The purity is worked on a 10-gram basis. The sample is thoroughly mixed and a definite amount accurately weighed by means of a chemicalbalance. The amount taken varies for different seeds, thus: For larger seeds, such as rye-grass,. 2 J grams ; for smaller seeds, such as crested dogstail, 1 gram ; for seeds such as rape, 5 grams ; for oats, prairie-grass, &c., 10 grams.. This weight is spread out evenly over a squared surface, and gone through carefully square by square with an eyeglass. All. extraneous seeds are picked out and weighed, and the percentage of extraneous seeds calculated thus :— ;1

Weight of extraneous seed 4- Weight of sample examined x 100 — Percentage by weight.

The remainder of the sample is then gone through for additional impurities, other than those noted in the weight, dissected. A list of all the impurities is made on the purity-card. .

The percentage by numbers is estimated as follows :— ........ 1 (1.) Weigh out definite amount of sample. ! (2.) Pick out extraneous seeds, weigh and count. (3.) Estimate number in 10 grams. (4.) Calculate per cent, by weight. (5.) Calculate weight of extraneous seeds in 10 grams. : (6.) Calculate weight of pure seeds in 10. grams. (7.) Estimate weight of 1,000 pure seeds. - . (8.) Estimate number of pure seeds in weight of pure seeds in 10 grams of sample : ' - - Weight of pure seeds in 10 grams of sample - -? Weight of 1,000 pure seeds x 1,000 = Number of pure seeds in 10 grams of sample. / . . . (9.) Estimate total number of seeds in 10 grams of sample. (10.) Then,

Number of extraneous seeds Total number of seeds x = Percentage by numbers of extraneous seeds.

Recording of Progressive Germination

The seeds that have germinated are counted out and discarded, and an entry made on the card under the date on which the count was made. : ,

Reporting.

In each case after the second count an interim report is furnished to the sender. This gives the average germination after a certain specified number of - days, and the percentage of impurities (if a purity test is desired). From the interim report it is expected that a merchant will be able to judge whether or not the line under consideration is fit for his trade. A very fair idea of what the final germination result will be is afforded by the use of pur progressive germination tables supplied to each merchant. Thus, for instance, a rye-grass germinating, say, 75, per cent, in six days will finish up with a test of approximately 80 per cent. This final result can be judged from the table.*

The interim report is an extremely valuable report, as it is so expressive of the vitality of the line. The rapidity with which germination takes place is a very important factor in determining the value of that line. Rapid germination means great vitality, and this is shown by the interim report. A good viable swede, for instance, will germinate over 90 per cent, of its maximum capacity in four days, whereas a poor germinating line may germinate less than 50 per cent, of its maximum capacity in the same period. It is highly probable that of those seeds which germinate after the interim report in such a line very few will come up when sown in the held. Final reports on germination are sent out at the expiration of the testing period, and in the case of purity tests the percentage and a complete list of the impurities. In order that the sender of the seed may decide the nature of the impurities present a list of extraneous seeds, some 226 in number, has been compiled,f and is supplied to those concerned. The English and the botanical name is given, and a key by which the relative harmfulness or otherwise can be judged.

Each sample is reported on individually, and the certificate is issued immediately the test of this particular sample is complete, irrespective of the number and kinds of other samples that may be included under any one advice of the sender.

In the case of clover-seeds, after the testing-period has expired there frequently remain few or many seeds that have neither rotted nor germinated. Such seeds are termed “ hard ” seeds. This “ hardness ,f is very common in freshly harvested lines of clover-seed. Heavy machine-dressing should reduce the number of hard seeds for immediatepurposes, but in the course of time natural “ softening ” will take place. Hardness in clovers is due to the impermeability of the seed-coats towater, and unless such coats are scratched by going through the-dressing-machine or through special scratching-machines no water can enter, and consequently no growth can take place, the seed remaining hard as when first put to test. In making up our final germination results half of the.“hard” seeds are allowed as viable.

Accounts. ■ ' : At the end of each month the record-cards are forwarded to the Department's Accountant, who renders the accounts and receives thefees.. • . ■ ■ .<• .: * A 'description of this method, together with the full tables, was published under the title of “ A Seed-testing Key,” in the -Journal for August, 1916. - ■ • •f For list see “ Seed Impurities,” in September, 1916, Journal.

Year ended March, ■Samples. Year ended Samples. ■ f Samples. Year ended March, ' March, March, . Samples. 1910 180 1915 2,646 I9II .. . 400 1916 .. 3,200 1912 ' . . 400 1917 .. 2,700 1913 . . . 650 . 1918 . . •• 3,859 1914 •• 1,863

During the year of inception 180 samples. were tested.- The following table indicates the growth of the work from its inception to the present time :-

Crucifers, clovers. . ■ Days. ' . . 2 Days. 4 . Days. 7 Days. 10 Rye-grasses ' • • 3 6 IO 14 Crested dogstail ... ... 4 8 12 . 18 ’ Cocksfoot ... • • 5 . 10 16 22

Four counts are made of each sample, but the interval between each count varies according to class of seed under test. Thus—-